I don't recommend used guitars at all. Most of them have warped necks, and can't carry a tune worth *****.
I recommend starting with Acoustic. Acoustic guitars are much harder on the fingers, don't hold notes as well, and thus are perfect for beginners. It's like learning to drive in the winter time - if you can learn on that, driving in the summer will be nothing. Same goes with guitars. If you learn on electric, you'll NEVER be able to play an acoustic. If you learn on acoustic, picking up an electric guitar will be easy as pie.
But, if your friend insists on starting out with an electric, I highly recommend a brand called Epiphone. It's basically a Fender Stratocaster clone for about half the price. They are very well made, generally run in the $300 - $400 range, have a tight, slightly curved neck for good neck action, and generally stay in tune longer than the flat-necked guitars. They are great for people with smaller hands as well.
If your friend has long fingers, or is quite tall, my personal favorite guitars are the Jackson Charvel series. Those are expensive as hell though - anywhere from $700 for a piece of crap up to $2500 for a dream guitar.
But, if she likes the feel of an Epiphone, and can afford the genuine Fender, go for the Fender.
If possible, tell your friend to shop around for a 24-fret guitar instead of the standard 22. I have a crappy Yamaha, but it's a 24 fret, so I refuse to get rid of it.
Hope this helps!